1. Field of the Invention
The present invention relates to a direct current brushless motor of a radial air-gap, having a larger sensing area, and the coating wire of the stator coil is easily drawn outward for installation.
2. Description of the Related Art
A first conventional direct current brushless motor in accordance with the prior art shown in FIG. 1 comprises a metallic shaft tube 901 having an outer wall combined with a coil 902, upper and lower pole plates 903, 904, and a circuit board 905. The metallic shaft tube 901 includes a flange 906 at one end thereof. By such an arrangement, the upper and lower pole plates 903, 904 are formed by laminated silicon plates for increasing the magnetic sensing area between the upper and lower pole plates 903, 904 and the permanent magnet 908 of the rotor 907. Thus, increase of the number of the pole plates will increase the working process of fabrication, the material, and the cost of the product.
A second conventional direct current brushless motor in accordance with the prior art shown in FIG. 2 is disclosed in U.S. Pat. No. 4,891,567, wherein the upper and lower pole plates 911 are combined on the stator seat 910. Each of the upper and lower pole plates 911 has vertically bent pole faces 912 which are induced with the permanent magnet 914 of the rotor 913. The two pole faces 912 of the upper and lower pole plates 911 are extended toward each other, so that two pole faces 912 of the upper and lower pole plates 911 encompass the outer periphery of the stator seat 910. The pole faces 912 of the upper and lower pole plates 911 have a larger sensing area. However, when the distal end of the coating wire of the coil is drawn outward from the pole faces 912 of the upper and lower pole plates 911, the insulation layer of the coating wire are easily scraped and broken by the coarse edges of the pole faces 912, so that the coil winding is easily broken after it is impacted by the starting current during long-term utilization, thereby affecting operation of the motor, and thereby reducing the lifetime of the motor. In addition, if the width of the pole face 912 of the upper and lower pole plates 911 is decreased to facilitate pulling out of the distal end of the coating wire of the coil, the sensing area between the pole face 912 and the rotor is reduced, thereby decreasing the quality of the motor during fabrication.
A third conventional direct current brushless motor in accordance with the prior art shown in FIG. 3 is disclosed in the Applicant""s U.S. patent application Ser. No. 09/389,018, wherein the first pole plate 921 is provided with a magnet conducting tube 922 for combination of the second pole plate 924. The outer wall of the magnet conducting tube 922 is fitted with an insulating bushing 923 which may be wound with a coil. The first pole plate 921 and the second pole plate 924 are respectively provided with pole faces 925, 926 each extended toward an opposite direction. Thus, the direct current brushless motor and the stator have pole faces with a larger sensing area, and the coil is directly wound around the insulating bushing 923, so that the coating wire is not easily scraped, thereby preventing the insulation layer from being broken.
The primary objective of the present invention is to provide a direct current brushless motor of a radial air-gap, wherein the pole plate of the stator has pole faces with a larger sensing area to induce with the permanent magnet of the rotor, thereby increasing the output torque of the motor.
Another objective of the present invention is to provide a direct current brushless motor of a radial air-gap, wherein the pole faces around the coil seat are formed with larger openings for facilitating pulling out of a distal end of a coating wire of the coil seat, thereby preventing the coating wire from being scraped, and thereby preventing the insulation layer from being broken, and the stator has pole faces with a larger sensing area.
A further objective of the present invention is to provide a direct current brushless motor of a radial air-gap, which is easily machined, thereby decreasing the cost of production.
In accordance with the present invention, there is provided a direct current brushless motor of a radial air-gap includes a rotor having a rotation shaft rotated in a magnetic conducting tube of the stator. The magnetic conducting tube has an outer wall combined with a coil seat. The coil seat has two ends respectively mounted with an upper pole plate and a lower pole plate. Each of the upper pole plate and the lower pole plate has a periphery having upper pole faces and/or lower pole faces respectively extended upward and downward therefrom. Each pole face is induced with the permanent magnet of the rotor. The pole faces of the upper pole plate and the lower pole plate are arranged in a staggered manner. The pole faces encompassing the coil seat are formed with larger openings for allowing pull out of a distal end of a coating wire of the coil seat.